An existing shortcoming of current optical disk players is the possibility of the players to effectively enter an infinite loop while playing music or other audio data stored on a disk. Such “skipping” may yield frustrating noises being produced by the player and an annoyance to the audio listener(s).
Existing technologies attempt to address specific difficulties encountered by optical disk players. For example, U.S. Pat. No. 6,912,189 discloses a method for managing defects that may cause an error during a write operation in a write-once data storage disk by maintaining a list of bad addresses. The method detects errors that may occur during the write operation and updates a “skip list” that contains the addresses of physical sectors on the disk that are to be skipped during a read operation.
Another reference executes multi-track read and write operations by embedding pointers that define the location of the next defect anywhere on a given cylinder surface in either the forward or backward direction. See, IBM Technical Disclosure Bulletin, “Defect Skipping Among Fixed Length Records in Direct Access Storage Devices”, pp. 1424-1426, September 1976. In the backward direction, the location of the next defect is measured from the track index of the current track. A look-ahead feature allows comparison between the length of a sequence to be read or written and the likelihood of intercept with the defect location, and allows for changing the command list for either skipping the defect or substituting an alternate clock location by an appropriate change in the commend list driving the direct access storage device (DASD).
However, such existing methods and systems rely on specific, non-standardized storage location and data structures for maintaining defect data. For example, disks compatible with these systems require forward-backward pointers for use with and audio disk. Accordingly, these solutions include an added layer of hardware or processing to address the problem of “skipping” that is not readily adaptable to the majority of current disk players.
Many optical disks currently have elements of error-checking, such as Cross-interleaved Reed-Solomon coding and Eight-to-Fourteen Modulation. Cross-interleaved Reed-Solomon coding provides a degree of error correction and detection through interleaving and interpolation. Under Eight-to-Fourteen Modulation the data to be stored is first broken into 8-bit blocks. Each 8-bit block is translated into a corresponding 14-bit codeword using a lookup table. The modulation ensures that the disk's binary coding sequence includes at least two zeroes between every two ones, thereby providing that every pit and land is at least three bit clock cycles long. However, neither of these approaches address the problem of nor prevent skipping due to post-write excessive damage of the disk. Rather, these methods provide for correcting known data errors to be corrected.
U.S. Pat. No. 7,215,608 discloses an apparatus for optical disk reproduction that compensates for a tracking error by using a real-time repetitive control and a method of driving the optical reproducing apparatus. The optical disk reproducing apparatus repetitively compensates for the tracking error in a real time, and the apparatus performs the error correction once per rotation of the disk and does so by calculating tracking errors derived from observations of the physical disk and the motor that spins the disk. However, the apparatus relates specifically to optical disk reproduction that compensates for a tracking error. This approach does not use a real-time code at the time of playback, which is typically contained in most audio CDs, nor would this approach address the issue of skipping for standard audio CDs that are already created or for CDs that are scratched or damaged after they are created.
Accordingly, there is a need in the art of a method and system to prevent or reduce excessive skipping on audio disks. Further, there is a need to provide a method and system that can reduce excessive skipping on audio disks that is capable of either leveraging existing audio disk players and audio disks or being readily incorporated into newly manufactured audio disk players.